SQL Server Timeout expired when update, delete or insert record but not when select

The error message you provided, that is a command timeout issue. Alternatively you can say, "SQL Server took too long to execute the insert/update/delete command". You can try to set the timeout to be longer which means that it takes longer for the client to realize that the server.

You can also look into improving performance on the server(Basically Insert/Update/Delete queries). It depends on the task and importance of the operation.

Refer SqlCommand.CommandTimeout[^] property for more information.

--Amit